Elimination of end-of-range and mask edge lateral damage in Ge+ preamorphized, B+ implanted Si

Abstract

The problems of residual extended defects due to end-of-range ion implantation damage and mask edge lateral damage have been solved in this study for shallow boron junctions preamorphized via germanium ion implantation. Defect elimination has been achieved by adjusting the germanium ion energy, dose, and annealing temperature and ambient to minimize the local interstitial point defect concentration and optimize the role of the free surface in defect annihilation. For the combination of shallow, low dose 40 or 60 keV/2×1014 cm−2 Ge+ and 8 keV/1×1015 cm−2 B+ implants, a defect-free structure was obtained following a 1050 °C, 10 s rapid thermal anneal (RTA) in a nonoxidizing Ar ambient. For these samples, boron profiles determined using secondary ion mass spectroscopy (SIMS) showed the junction depth to be approximately 0.17 μm at a background doping of 1×1017 cm−3 with a sheet resistance of 136 Ω/⧠.